.\" Copyright 2003 Walter Harms, Andries Brouwer
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" Distributed under GPL
.\" %%%LICENSE_END
.\"
.TH FDIM 3 2021-03-22 "" "Linux Programmer's Manual"
.SH NAME
fdim, fdimf, fdiml \- positive difference
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double fdim(double " x ", double " y );
.BI "float fdimf(float " x ", float " y );
.BI "long double fdiml(long double " x ", long double " y );
.fi
.PP
Link with \fI\-lm\fP.
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR fdimf (),
.BR fdiml ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
.fi
.SH DESCRIPTION
These functions return the positive difference, max(\fIx\fP-\fIy\fP,0),
between their arguments.
.SH RETURN VALUE
On success, these functions return the positive difference.
.PP
If
.I x
or
.I y
is a NaN, a NaN is returned.
.PP
If the result overflows,
a range error occurs,
and the functions return
.BR HUGE_VAL ,
.BR HUGE_VALF ,
or
.BR HUGE_VALL ,
respectively.
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Range error: result overflow
.I errno
is set to
.BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR fdim (),
.BR fdimf (),
.BR fdiml ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.SH BUGS
Before glibc version 2.24
.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6796
on certain architectures (e.g., x86, but not x86_64)
these functions did not set
.IR errno .
.SH SEE ALSO
.BR fmax (3)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
